Search results for "microbiology"
showing 10 items of 7546 documents
Global diversity and geography of soil fungi
2014
Fungi play integral roles in soil nutrient cycling, but the determinants of fungal diversity and biogeographic patterns of key functional groups remain poorly understood. By using pyrosequencing data from hundreds of globally distributed soil samples, we demonstrated fungal diversity that expands upon the taxonomic and molecular diversity recorded so far. Except for ectomycorrhizal symbionts, fungal functional group richness was unrelated to plant diversity and plant-to-fungus richness ratio declined exponentially towards the poles. Climatic factors, followed by edaphic and spatial variables, constituted the best predictors of fungal richness and community composition at the global scale. F…
The influence of bacteria-dominated diets on Daphnia magna somatic growth, reproduction, and lipid composition
2012
We explored how dietary bacteria affect the life history traits and biochemical composition of Daphnia magna, using three bacteria taxa with very different lipid composition. Our objectives were to (1) examine whether and how bacteria-dominated diets affect Daphnia survival, growth, and fecundity, (2) see whether bacteria-specific fatty acid (FA) biomarkers accrued in Daphnia lipids, and (3) explore the quantitative relationship between bacteria availability in Daphnia diets and the amounts of bacterial FA in their lipids. Daphnia were fed monospecific and mixed diets of heterotrophic (Micrococcus luteus) or methanotrophic bacteria (Methylomonas methanica and Methylosinus trichosporium) and…
Diverse societies are more productive: a lesson from ants
2012
The fitness consequences of animal personalities (also known as behavioural syndromes) have recently been studied in several solitary species. However, the adaptive significance of collective personalities in social insects and especially of behavioural variation among group members remains largely unexplored. Although intracolonial behavioural variation is an important component of division of labour, and as such a key feature for the success of societies, empirical links between behavioural variation and fitness are scarce. We investigated aggression, exploration and brood care behaviour in Temnothorax longispinosus ant colonies. We focused on two distinct aspects: intercolonial variabil…
Exclusion of Saccharomyces kudriavzevii from a wine model system mediated by Saccharomyces cerevisiae.
2010
This study investigated the competition and potential hybrid generation between the species Saccharomyces cerevisiae and S. kudriavzevii in a wine-model environment. Our main goal was to understand why S. kudriavzevii has not been found in wine fermentations whilst their hybrids are present. Auxotrophic mutants (Ura(-) and Lys(-)) were used to favour the selection of hybrids and to specifically differentiate the two species in mixed fermentations carried out at different temperatures (17 °C, 24 °C and 31 °C). Both yeasts showed a reduction in their maximum specific growth rates in mixed fermentations, indicating a clear antagonistic effect between the two microorganisms. Temperature played …
Intraguild interactions between egg parasitoids: window of opportunity and fitness costs for a facultative hyperparasitoid.
2013
We investigated intraguild interactions between two egg parasitoids of Nezara viridula (L.) (Heteroptera: Pentatomidae), Ooencyrtus telenomicida (Vassiliev) (Hymenoptera: Encyrtidae) and Trissolcus basalis (Wollaston) (Hymenoptera: Platygastridae), as the former has the potential to be a facultative hyperparasitoid of the latter. We assessed the suitability of N. viridula eggs for the development of O. telenomicida as a function of egg age when they were unparasitized, or had been attacked by T. basalis at different times prior to exposure to O. telenomicida females. Ooencyrtus telenomicida can exploit healthy N. viridula host eggs up to 5 days of age, just prior to the emergence of N. viri…
In vitro antitumor effects of the cold-water extracts of Mediterranean species of genus Pleurotus (higher Basidiomycetes) on human colon cancer cells
2014
The aim of this study was to evaluate whether the cold-water extracts of Pleurotus eryngii var. ferulae (CWE-Pef) and Pleurotus nebrodensis (CWE-Pn), 2 of the most prized wild and cultivated edible mushrooms, can affect the tumor phenotype of human colon cancer HCT116 cells. Our results showed that treatment with CWE- Pef and CWE-Pn resulted in a significant inhibition of the viability of HCT116 cells and promoted apoptosis, as also demonstrated by the increase of Bax-to-Bcl-2 messenger RNA ratio. Moreover, we observed that both extracts were able to inhibit cell migration and to affect homotypic and heterotypic cell-cell adhesion. It also was found that treatment with CWE-Pef and CWE-Pn ne…
Granulocyte Activity Is Enhanced by Culture Supernatants of Mononuclear Leukocytes Incubated with Tetrachlorodecaoxide
1995
Granulocytes (polymorphonuclear leukocytes, PMNs) and monocytes/ macrophages are important in wound healing. Within the first few hours PMNs and monocytes begin to infiltrate sites of injury. The major function of PMNs is to kill microbes and phagocytose cellular debris so that healing can proceed [1]. Monocytes/macrophages invading the wound are also active in phagocytosis. In addition they release a number of cytokines including growth factors, interleukin-8 (IL-8), and tumor necrosis factor (TNF-α) needed for new tissue formation and shown to stimulate PMNs [1–3].
Norovirus infections and seroprevalence of genotype gii.4-specific antibodies in a spanish population
2015
Genotype II.4 noroviruses (NoVs) are a leading cause of epidemic acute gastroenteritis in children and adults worldwide. The prevalence of different NoV genotypes causing outbreaks and sporadic cases of acute gastroenteritis in the region of Valencia, Spain, during a 4-year period (2008–11) was investigated. NoVs were detected in 42 out of 55 (76.3%) outbreaks and in 26 out of 332 (7.8%) sporadic cases of acute gastroenteritis. Genogroup GII strains were predominant in outbreaks and sporadic cases. Different genotype GII.4 variants were found (Yerseke_2006a, Den Haag_2006b, Apeldoorn_2007, and New Orleans_2009), with the latter variant detected most frequently (35.3%). A recombinant P domai…
In vivo evaluation of the interaction between the Escherichia coli IGP synthase subunits using the Bacterial Two-Hybrid system
2020
ABSTRACT Histidine biosynthesis is one of the most characterized metabolic routes for its antiquity and its central role in cellular metabolism; indeed, it represents a cross-road between nitrogen metabolism and de novo synthesis of purines. This interconnection is due to the activity of imidazole glycerol phosphate synthase, a heterodimeric enzyme constituted by the products of two his genes, hisH and hisF, encoding a glutamine amidotransferase and a cyclase, respectively. Despite their interaction was suggested by several in vitro experiments, their in vivo complex formation has not been demonstrated. On the contrary, the analysis of the entire Escherichia coli interactome performed using…
Different species and symbiotic genotypes of field rhizobia can nodulate Phaseolus vulgaris in Tunisian soils.
2002
Abstract A collection of 160 isolates of rhizobia nodulating Phaseolus vulgaris in three geographical regions in Tunisia was characterized by restriction fragment length polymorphism analysis of polymerase chain reaction (PCR)-amplified 16S rDNA, nifH and nodC genes. Nine groups of rhizobia were delineated: Rhizobium gallicum biovar (bv.) gallicum, Rhizobium leguminosarum bv. phaseoli and bv. viciae, Rhizobium etli bv. phaseoli, Rhizobium giardinii bv. giardinii, and four groups related to species of the genus Sinorhizobium, Sinorhizobium meliloti, Sinorhizobium medicae and Sinorhizobium fredii. The most abundant rhizobial species were R. gallicum, R. etli, and R. leguminosarum encompassing…